Movement of a prey is different between the living and the dead. The dead is indifferent even when a predator is approaching, because the matter of life or death is already out of his interest. This "indifference" is seen from the other side's point of view: living being's.
In addition, movement of a creature in the upper level of an ecological pyramid is different from the lower ones. An eater catches his prey to live, and the prey is caught. Also, the volume of food becomes larger or smaller, and food turns clockwise or counter-clockwise depending on an eater.